Radiation damage to amino acids and proteins and to chromatin extracted from cultured Chinese hamster lung fibroblasts is being studied. In general irradiations are carried out in aqueous solution so that free radicals produced from water, OH., e- sub ag, H. and 02-, are the damaging species. The relative efficiencies of the individual radicals for radiation damage are being evaluated. Radiation-induced DNA-protein cross linking has been found in irradiated, isolated chromatin and in chromatin irradiated in the cell before isolation and the specific chromosomal proteins involved in the cross linking process are being determined. Polyacrylamide gel electrophoresis containing SDS is being used to characterize the histones and to determine changes in histone interaction in chromatin. The interaction of the polypeptide hormone, glucagon, and selected amino acids irradiated in solution is being studied. The binding of phenylalanine, tryptophan and tyrosine appears to be mediated through hydroxyl radical attack, whereas, for histidine, methionine and alanine the solvated electron and hydroxyl radical are equally effective for the formation of adducts. These adducts are being examined with peptide analysis to determine the binding sites of amino acid to glucagon so as to determine if the binding is random or specific.